This invention is directed to supports utilized for making spectroscopic measurements and other studies which utilizes polystyrene or other aromatic containing polymers which are derivatized in such a manner so as to maintain the spectroscopic clarity of the support.
Polystyrene is one of the most used of all polymers. It is utilized either as pure polystyrene or in conjunction with a copolymer. Further, derivatives of polystyrene are known, such as chloromethylated polystyrene.
Polystyrene and its copolymers are soluble in most of the normal organic solvents with the exception of the lower alcohols. Other solvents swell or gel polystyrene and copolymers of polystyrene. The swelling action of many solvents on polystyrene allows for the use of polystyrene as the support matrix for resirs utilized for chromotography, ion exchange and the like.
Appropriate functional groups can be introduced into the aromatic rings of the polystyrene by one of two methods. The first is the actual polymerization of monomers which incorporate these functional groups. U.S. Pat. No. 3,872,067 describes a process for preparing a chloro-methylated polystyrene divinyl benzene copolymer utilizing appropriate polymerization of the preformed chloro-methylated polystyrene monomer.
For preparing derivatives of polymerized polystyrene, it is necessary to swell the polystyrene matrix such that pores and the like are formed in the polystyrene matrix allowing for introduction of the appropriate functional groups within the interior of the polystyrene bead or the like. U.S. Pat. No. 3,956,219 describes this process arid discusses the problems with regard to the same. In this patent the polystyrene is being substituted with certain peptide functionalities which have different solvent properties compared to the polystyrene. As the patent describes, in utilizing certain solvents such as methylene chloride, the polystyrene is extended, but the peptide functionalities are not soluble in this solvent or other similar solvents. The solution of U.S. Pat. No. 3,956,219 is in the use of N-methyl-2-pyrrolidone which acts both as a swelling agent for the polystyrene and as a solvent for the peptide groups.
U.S. Pat. No. 3,8860,486 describes the use of polymethylated styrene as a matrix for insolubilizing certain enzymes by reacting the chloromethyl groups with 2,5-dioxo-4-oxazolidine. The water soluble enzymes react with the oxazolidine group to insolubilize the same. This patent is characteristic of certain procedures wherein biological molecules can be manipulated by the absorption, attachment or reaction of the same with a suitable insoluble matrix such as a derivatized polymer or the like.
Both U.S. Pat. Nos. 3,974,110 and 3,995,094 discuss Freidel-Crafts substitution reactions for the introduction of chloromethyl groups onto the aromatic ring of polystyrene. In the body of U.S. Pat. No. 3,995,094 discussion is set forth as to problems with regard to solvents which can be utilized for such Freidel-Crafts modifications of polystyrene. Organic solvents such a benzene, toluene, zylene and the like themselves would undergo the halomethylation reaction and thus are not useful as solvents. The alcohols, diols and the like deactivate the normal Lewis acids utilized as catalysts in these reactions. Noted as acceptable solvents for the halomethylation of polystyrene are carbon disulfide and nitroalkanes and nitroaranes and the lower haloalkanes.
The above patents are directed to the reactions specified. therein with little consideration given to the actual final use of the polystyrene article. Thus, while carbon disulfide and chloroform might be suitable for Freidel-Crafts reactions on polystyrene, they could not be utilized if a polystyrene article was to be maintained in the same physical form after the reaction as it was before the start of the reaction.
U.S. Pat. No. 4,226,958 converts polystyrene to bromopolystyrene by bromination with bromine in carbon tetrachloride. The brominated polystyrene is then further reacted in other solvents to form certain organo-arsenic derivatives of the polystyrene. Again, as with the reactions discussed above, during the bromination step utilizing carbon tetrachloride little consideration is given to maintaining certain physical properties of the polystyrene such as optical clarity, optical surfaces and the like during the reaction thereon.
Because polystyrene can be derivatized such as by the formation of chloromethylated polystyrene, and because it is a transparent solid, it has been determined that polystyrene, polystyrene plus other copolymers, or other aromatic moiety containing polymers which also are optically clear, could be useful for support mediums for certain spectroscopic studies. However, in order to so utilize these polymers for this purpose, consideration must be given to maintaining the optical clarity of these supports and preventing salvation, geling, swelling, etching, or other physical changes to the support medium during any reaction on the polystyrene itself or on subsequent derivatives of polystyrene. It is to this end that this invention is directed.
It has been determined that, by reacting polystyrene with suitable chemical reactants under certain conditions the optical properties of a polystyrene article can be maintained. Furthermore, it has been determined that by reacting polystyrene with certain reactants in the presence of certain solvents that reaction of the polystyrene in a preformed article can be limited to the surface of the article. This avoids derivatizing the total matrix of the polystyrene such that upon further reaction of the derivatized polystyrene with large molecules which are unable to penetrate the polystyrene matrix, the derivative groups to which the large molecules are attached also do not interfere with the spectroscopic properties of the polystyrene article.
In view of this it is a broad object of this invention to provide a process for initially introducing a functionality onto polystyrene or other aromatic group containing polymers utilizing a solvent system which maintains the optical integrity of the polystyrene and by not solvating, swelling, gelling or otherwise interacting with the main body of the polymetric article, limits the derivation of the aromatic moieities of the polymer to the surface of the article. It is a further object of this invention to provide support surfaces formed of polystyrene or other like polymers which contain aromatic moieties which are useful in supporting or holding biologically interesting molecules or useful in attaching those molecules to a support surface such that the molecules can be further derivatized and/or spectroscopically tagged, i.e. made to flouresce and the like, in order to study these molecules.
These, and other objects, as will be evident from the remainder of this specification are achieved in a process of derivatizing only the surface of an article formed of a polymer containing an aromatic moiety by introducing a substituent group onto said aromatic moiety which comprises: contacting said surface of said article with a reaction mixture wherein said reaction mixture contains tetramethylene sulfone as the solvent of said reaction mixture and further includes a reagent containing said substituent group; maintaining said reaction mixture in contact with said surface of said article to introduce said substituent group onto at least a portion of said a romatic moieties of said polymer located on said surface of said article; isolating said article from said reaction mixture.
The article of the preceding paragraph can be additionally reacted on wherein said substituent group is chosen from the group consisting of halo, haloalkyl, acyl and formyl and further including; contacting said isolated article with a further reaction mixture wherein said further reaction mixture contains one of the group consisting of tetramethylene sulfone, dimethyl disulfoxide or aqueous media as the solvent in said further reaction mixture and said further reaction mixture includes a reagent containing a nucleophile; maintaining said further reaction mixture in contact with said surface of said article to substitute the halo function of said halo and alkyhalo substitutent groups and the keto function of said formyl and said acyl substituted groups with said nucleophile; isolating said article from said further reaction mixture.
Additionally, the objects of the invention can be achieved in an article formed of polystyrene wherein on the surface of the article includes haloalkyl or acyl substitution groups, a process of derivitizing the halo alkyl or acetyl groups without destroying the spectroscopic clarity of the article which comprises: contacting said article with a reaction mixture wherein said reaction mixture contains one of the group consisting of tetramethylene sulfone, dimethyl sulfoxide or aqueous media as the solvent of the reaction mixture and further includes a reagent containing a nucleophile; maintaining said further reaction mixture in contact with said surface of said article to substitute the halo function of said halo and said haloalkyl substitutent groups and the keto function of said formyl and said acetyl substituent groups with said nucleophile; isolating said article from said reaction mixture.
By initially derivatizing polystyrene or a like aromatic containing polymer in the presence of tetramethylene sulfone, by essentially an electrophilic substitution reaction, the aromatic moiety of the polystyrene or other aromatic containing polymer is derivatized with a functional group on the surface of an article, while still maintaining the integrity of the article with respect to certain properties such as optical or spectroscopic clarity. Further, by not swelling, gelling or otherwise expanding the polymetric matrix, the dimensions of the article can be maintained within an acceptable tolerance. The group which is electrophilically substituted onto the aromatic moiety of the polystyrene or other aromatic containing polymers can be further reacted on if it is chosen so as to include a site of reactivity. Thus, the keto function of the formyl or acetyl groups is susceptible to further reaction utilizing known standard reaction sequences. Further, the halo groups on a halo-polystyrene or similar aromatic moiety containing polymer or a haloalkyl polystyrene or other aromatic moeity containing polymer is susceptible to substitution reactions also in a known manner. However, in undertaking these further reactions, consideration must again be given to maintaining the optical or spectroscopic integrity of the basic article.
For the initial substitution of the aromatic ring, not only must solvent effects of the polystyrene or other aromatic containing polymer be considered in order to avoid distortion of the basic properties of the article, but further consideration with regard to the solvent must be given to the reaction itself such that the solvent does not interfere with the basic reaction. As such, solvents which themselves can serve as reacting species are precluded and solvents such as Lewis bases, alcohols, aqueous solvents, ethers and the like which would serve as terminators or catalytic poisons for the basic reaction, must also be avoided.
In subsequently reacting the substituted polystyrene or other aromatic polymer with a further reaction, the considerations with regard to the solvent effects on the article itself must be maintained. However, the nature of the solvent being reactant itself is modified from the original electrophilic substitution of the aromatic moiety.
For the initial electrophilic substitution reaction, tetramethylene sulfone is the solvent chosen. For the additional reactions further solvents in addition to tetramethylene sulfone can be utilized. These include dimethyl sulfoxide and aqueous based reaction media.
Preferredly, once the original substituent group is introduced onto the polystyrene or other aromatic moiety containing polymer, the second substituent group then reacted with the first substituent group would be a difunctional substituent group such that the first functionality of this second group would react with the first, or primary substituent attached to the polystyrene. or other aromatic moiety of the polymer with the further substituent then available as an additional reaction site to attach other groups to the article. These other groups would generally be selected from biologically interesting molecules such as peptides, proteins, enzymes, antibiotics, sugars, nucleic acids and the components thereof, starches and lipids, and further cells, cell membranes viral proteins and the like might also be attached by utilizing binding sites on the surface of the cell, c ell membranes, viral proteins and the like to react with the further functionality of the difunctional subsequent group which is attached to the primary substituent group on the polystyrene or aromatic moiety of a similar polymer.
Agents which are capable of interacting with biologically interesting molecules, such as flourescing agents, dyes and the like, can additionally be reacted with the biologically interesting molecule attached to the article in the same solvent systems as were noted for attaching the biologically interesting molecule itself.
Insofar as tetramethylene sulfone (TMS) is an excellent solvent for Lewis acid catalysts s uch as stannic bromide and the like, Freidel-Crafts acylations and alkylations can be utilized to derivatize polystyrene or other polymer containing an aromatic moeity. Thus, typical Freidel-Crafts alkylation reactions can be run such as attaching a bromomethyl group to polystyrene utilizing stannic bromide and bromomethylmethyl ether and typical Freidel-Crafts acylations can be run utilizing the same Lewis acid, stannic bromide, and acetyl bromide to acetylate the aromatic ring of polystyrene. In a like manner, higher haloalkyls and higher acetyls can be introduced.
For both alkylations and acylations aside from stannic bromide or chloride other Lewis acids such as boron trifluoride, aluminum chloride, ferric chloride, zinc chloride and the like can also be considered. Formylation of the polystyrene could be effected utilizing formylation reactions such as carbene intermediates formed in a Reimer-Tiemann reaction or, alternately, Gattermann-Koch or Vilsmeyer reaction can be utilized to introduce the formyl group onto the aromatic moiety of the polymer. Normally, other activating groups could also be present on the aromatic moiety to facilitate the formylation reactions such as using a phenolic or xylene based polymer.
For the introduction of a nitro, sulfonyl or diazo group onto the polystyrene or other aromatic moiety of a basic polymer, a standard electrophilic substitution reaction would be undertaken.
Insofar as higher aromatic compounds such as napthalene, anthracene and the like are also susceptible to these electrophilic reactions, polymers which incorporate these as aromatic moieties would also be susceptible to these electrophilic substitutions in order to derivatize the same only on the surface of an article formed of these polymers without distortion of the article by polymetric swelling, gelling, solvation or the like.
For subsequent reactions on the article once the primary substituent group is located thereon, typical nucleophilic reactions are utilized. As such, the halogen of a halo or haloalkyl primary substituent group can be easily displaced by nucleophilic substitution utilizing amines, alcohols, thiols, hydrazines, phenols, anilines and the like. Additionally, water, ammonia, hydrogen sulfide, disulfides, phosphates and other typical reactants could be utilized.
Alternately, biologically important molecules such as peptides, proteins, enzymes, antibiotics, sugars, nucleosides, nucelotides, nucleic acids, starches and lipids including steroids, terpines, fatty acids, phosphotides, glycolipids, aliphatic alcohols and waxes could also be utilized by taking advantage of a reactant group on these molecules to interact with the reactant group on the primary substituent attaching to the aromatic moiety of the polymer on the surface of the article.
Normally, for laboratory identification, medical testing purposes and the like, a difunctional group would be attached to the primary substituent utilizing a first functionality of the difunctional group to attach to the primary substituent and leaving a second functionality of the difunctional group open so as to provide a further reactant site for attachment of the above biologically important molecules. Any typical difunctional group containing amines, alcohols, thiols, hydrazines, disulfides and the like could be utilized. Also, molecules which can serve as a biological indicators either by a particular biological reactivity or by exhibiting a chemical or physical effect such as fluorescence or color change could further be attached.
In all of the above, standard chemical reaction conditions would be maintained with the exception that all reactions, whether they are the introduction of the primary substituent on to the aromatic moiety of the polymer or subsequent additions to this primary substituent are performed in solvent systems which do not gel, swell or solvate the polymer such that the integrity of the article formed of the polymer with regard to at least optical and/or spectroscopic properties is maintained and is not detracted from. Excluded from consideration therefore as solvents are any solvents which swell, gel, solvate or otherwise interact with the polymer and which further interfere with the chemical reaction being performed on the polymer.